In many fields of endeavor, the ability to record visual images plays a significant part. Prior art devices for recording visual images are available in the form of devices which employ photographic film, and electronic devices for recording visual images such as the conventional TV camera, or more precisely, a vidicon tube, for example.
Essential to the production of a useful visual image is sufficient illumination intensity. The advent of the laser, with its intense output, has enabled the recording of events whose time duration is in the microsecond range, or less.
Some examples of visual recording devices employing laser illumination sources include Armstrong et al, U.S. Pat. No. 3,445,167; Guillet et al, U.S. Pat. No. 3,643,568; McCall, U.S. Pat. No. 3,485,159; and some of the cameras described in Huston's "High-Speed Photography and Photonic Recording" appearing in J. Phys. E:Sci. Instrum. Vol. 11, 1978, pages 601-609.
These and other prior art cameras employ a variety of techniques to record information on a visual record. For example, Huston discusses framing photography which produces one or more two-dimensional images of the subject, a species of framing photography is entitled multiple framing photography where a short sequence of two-dimensional images is recorded in such a way that it is not possible to project the result as a conventional movie-type presentation. He also discusses the conventional movie-type photography which produces a sequence of two-dimensional images so that projection can take place at a slower rate. In addition, streak photography dispenses with one spatial dimension and records, without interruption, the time variations of the image with respect to a single dimension only. Another technique employed in photography in general as well as in microsecond photography, is stroboscopic photography in which multiple images of a subject undergoing a periodic process are recorded at the same relative time into the process. Each of these techniques carries with it different requirements for illuminating the subject, processing the illumination from the subject and recording the same. Depending upon the particular type of equipment used to record the image, various changes must be made to adapt the equipment to operate under the different regimes.
Furthermore, and especially significant in microsecond photography, is the necessity for the equipment to be precisely timed with respect to the events sought to be recorded. The changes necessary in the recording equipment to effect this precise timing, for photographing different events or different occurrences of similar events, requires more or less effort depending upon the particular equipment employed, and the techniques that equipment employs to record the image.
It is one object of the present invention to provide a camera capable of effecting microsecond photography which is not only versatile in that essentially the same equipment can be employed to generate multiple framing photography, streak photography and stroboscopic photography, but is also relatively simply to alter from one regime to the next. It is another object of the present invention to provide a microsecond photography camera which is easily adjustable to capture precisely the images sought to be recorded, when those images may exist for time durations on the order of a microsecond, or less. It is another object of the present invention to provide a microsecond photography camera which is relatively simply to adjust in that the parameters whose adjustment is required to achieve the desired result, are easily controlled. These and other objects are met in accordance with the invention which will now be described below.